Fluid impact pulverizer



July 8, 1952 w. A. THOMAS 2,602,595

FLUID IMPACT PULVERIZER Filed Dec. 29, 1945 2. SHEETS- SHEET 2 INVENTO'RPatented July 8, 1952y FLUID INEPAC'I PULVERIZER William lA. Thomas.,Pittsburgh, Pa., assignonte .Blew-Knox C.ompa,ny,Pittsburgh,Pa.,acorporationof New Jersey rApplication December 29, 1945,SerialLNo'.-6?7,82,0.`

' 6V Claims. (Cl. 2211-939) This invention .relatesA to. apparatusgior-pulverizing solidsyby impact: .of particles with. veach other whiletraveling at;high. speed,.and to-means for. separating. and removing.the particles which Y2 Supplying nulverzedcoalier eembustioa ineluding`my invention;

Figure 2 is an elevation partly broken Aaway showing the pulverizer yofmy invention with 4a have been reduced; toxthe. desired neness', and 5.portion in.centralvertical.-section; returningthe;oversize:.particlesgfor further grind- Figure 3 is a verticalsection taken-.along the ing, plane of line .III- IIIof-Figure 2;!

Impact grinders orfpulverizersV utilizing a gas vFigurei isahorizontal'section takenalongthe under pressure asamotive zuidihave:been known` plane of line IV-IV of Figuref; heretofore buthavebe'enLsubject tocertain'limil0 Figure 5 is a portion of Figure 3 toenlarged tations. Itis the. objeetofzmyninvention to: proscale.; and lvide improved impact...-pulverizing apparatusof Figure .fi-isv a.. p artia1. horizontalsection.taken simple construction, capablegofeffectingthe along theplaneof linefVI-VI of Figure. 5. desired pulverizationJwithaminimunrconsump- 4Referring in',d'etail to the drawingatheinventionof :steam andl other Adesirable operating char.- 15. tionisparticularly .useful inithe xpulverization. of

acteristics such as fpreliminaryrrern'oval of dust or iinesfromthematerialtoi-be.pulverized,;uniformity in the neness oiftheproductatvarious rates of feed, and .the ability. to .grindmaterialhaving aconsiderable moisture. content, as readilyv as relatively. dry material.

. In a preferred.embodiment,.theinventioncomprises a closed. vessel,conveniently a f cylindrical tank, withits axis-vertical, apair;ofiopposed gasjet injectors infthe lowerpportionthereot and afeederthereabove'for. delivering `solidmaterial to be reduced in:theform Ioii coarse :particles Vor small'lumps for pnlverizatonbyzimpact. Above the .feeding means I provide a. classifier chamberhaving a vcircumferential inlet opening. Guide venes spaced aroundthennenins: impart; e tengentia'l Velocity component` to -thelentering gasstream entraning solidpafrticles of-.various sizes. An outletpipeextending centrally; i-nto the classifier.. permits theescapeofanarticleswhich have been reduced suiiiciently Vin sizeto iloa-tin .the outiiowinggas. The lower portion ofthe classieris-in the formcfa hopper for collecting over,- size particles Aand returning, themtothe-entering stream ofsolid material.` iniportantfea-ture oftheinvention is theprovision-Y of a positive downward force on vthe.oversizel particles which tends to insure eiectiveseparation. thereoffrom the liner iioating particles.

Further details, novelfeatures and advantages of the invention will beexplained during the fol!- lowing -complete description.,whih referstothe accompanying drawings illustrating a preferred embodiment of theinventionand a typcaL systeniin which it is..adapted.tolserveviaapparatus for supplyingr pulverize'dcoal to a, furnace.- Jforcombustion. i v i Y In the drawings:

Figure 11 is a. diagrammatic. elevaaenwitn la portion ingsection showing4et.Grilliplete system. Afor coalv for combustionalthough. it is-by nomeans limited to this specific @application It. will rbe described indetail, howevenl with .refe-rence. to such application. .AsshowninFigure 1,-the pulverizer indicated generallyfat l0. is adapted toreceive coal .from a storage hopper .H by means of. a screw conveyor ,l2which dischargesinto thev inletof a feeding mechanism .|3. .Thefeedingvmechanism is preferably ofthe injectortype dis.-

closed in detail and claimed in .my copending application, Serial No.637,319, filed December 29, 19.45, Patent No. v 1420;388 for ApparatusAfor FeedingGranular. Materialnto a Fluid Stream. Pulverized coal.produced by my inventionnows through a delivery- PipeMito as eparatorlv5fof known Aconstructioneiective to separate mostfo'f the coal fromthe vrnotixrefluid,usually.superheated steam. 'Ifhe- `coal falls into@burner-*i6 which is supplied with l air yfor Ocombustion-byfa blower Hthroughfiinpipe i8. v-'Ih u elandwair are ,1i-red inicia furnace.Greiner ce i9. 'Steam disehareedibv thefseeeraiorl iOWS through e einenwith eels/a smellfrertin 2f-ib@ Coal: into the. combustion .space l 9.Referring .HOW-1119K@ BatilllalyiOLFgllfS .2 throush for. a detaileddescription Qf; the .m11- verizer` il), it will be s een that. itcomprises. ai. cylindrical tank having 5.a vside wall l,y a bottoml` 22and a top er cavern. elisir .ef .ocpeeedieietors Haare. disposed inthetank at.-a levelsoinewhat. above` the.bottorngZZ.v Each injectorcoinprises a. nozzle 325 connected y to. .a suitable source of motivefluid, such 1assuperheated. steam,. andA athroatl. v'llrienozzle visinQuilted radially on the side. wa11pf-the taakwhuetne throat.vearried by. a strut: 2lv extendingv upwardly. from`the bottom. 22.shownrlthe. twoinjecto'rslare. axially alinedl and s ,pacedslightlyapartA Va result, lthey areadapted:tofdischarge-jets ofsteainand solid particles entrained therewith into direct or head-oncollision.

The feeding means I3, as previously stated, is of the injector type andincludes a Venturi throat 28 and a nozzle 29 connected to a suitablesource of gas under pressure such as superheated steam. Inaccordancewith well-known principles, the injector servestodischargeintfthe interior of the pulverizer I a jet of steam entraining solidparticles drawn in through the inlet indicated at 30 in Figure 1. In theparticular example being described, the solid material is coal which hasbeen initially reduced to particles of approximately 1/2 in diameter.The feeding means I3 has an outlet or mouth 3|.` Coal dischargedtherefrom strikes a concave deflector plate 32 mounted on the sidewall2| striking the defiector the coal particles rebound and fall downwardlywith some fragmentation and the resulting particles are, after a certainamount of eddying and helter-skelter circulation, entrained by the steamjets delivered to the injectors 24 by the nozzles- 25. As shown in thedrawings, the axis of the feeding mechanism I3 lies in a vertical planenormal to the vertical plane through the axes of the injectors 24. Theinjectors, as already stated, discharge jets of steam and particles intodirect collision whereupon further fragmentation of the particlesoccurs.

Any dust or similar fine particles accompanying the coal delivered intothe pulverizer by the feeding means I3 are floated upwardly by thegeneral movement of the steam within the pulverizer in that direction.'`Such material needs no further grinding and, because of its fineness,floats readily upward and is thus effectively separated from the largerparticles which are drawnjinto the injectors as just explained.Additional fine particles produced by the collision of ycoarserparticlesjin the space between the discharge en ds of the injectors 24also float upwardly in the ascendingmass of steam. Coarser particles mayaccumulate on the bottom of the pulverizer but 'are agitated by the jetsfrom injector 28, 29 and eventually are again drawn into the steamjets'of the' injectors 24 and subjected to vfurther impact. Thus all thematerial delivered to the pulverizer is progressively reduced to afineness such that it can escape by notation in the upwardly movingsteam.

A classifier 33 in the upper portion of the tank comprises-facylindrical chamber open at the top. The Achamber is supported from thecover 23 on hangers 34 so that the upper edge of the chamber is spaced asubstantial distance below the top of the tank, leaving acircumferential opening or inlet for steam and floating particles ofcoal orv other solids. An outlet 35 extends centrally through the top 23and downwardly intol the chamber 33 terminating at a level below theupper edge thereof. This outlet is connected to delivery pipe I4.vertically disposed guide vanes 3E are hinged at their outer edges in aring 3'| securedl to the top of the chamber 33 and a plate 38 securedtothe cover 23. A ring 39 having radial slots 4|] rests on the upperedges of the vanes 36. The vanes have projections 4| extending upwardlyfrom` their inner edges into the slots 49. Thus by slight angularmovement of the ring 39, the angular position of all the vanes may besimultaneously adjusted. To permit such adjustment, an actuating shaft42 having a` handle V43 Aisv secured to of the tank. On'

one of the vanes and extends upwardly through the cover 23.

The vanes 36 are adjusted to impart a tangential velocity component tothe steam and coal particles owing upwardly through the space betweenthe chamber 33 and the tank wall 2| and inwardly into the former. 'Ihiscreates a vortex in the chamber'from the center of which steam and fineparticles oating therein ascend through the outlet 35 and flow throughthe pipe I4 to the separator I5. Coarser particles which arrive in thechamber 33 are thrown outwardly by centrifugal force and thus removedfrom the steam ascending into the outlet 35. These coarser particlestravel around inside the chamber 33 and fall gradually into a hopper 44therebelow. The lower end of the hopper is connected to a branch opening45 in the outlet 3| of the feeding mechanism and thus returns thecoarser particles to. the entering stream of solid for further grindingby repeated impact as previously described. The jet of steam and solidmaterial delivered by the feeding means I3 creates a positive down draftthrough the chamber 33 and hopper 44 and thus prevents any tendency ofthe rising steam to pass through the classifier in the reversedirection.

It will be apparent from the foregoing that the invention provides apulverizer having numerous advantages-over similar devices knownheretofore. The apparatus-is simple and compact and requires noparticularr attention during operation. The continuouscirculation ofsolid material repeatedly through` theropposed injectors causes it to beprogressively reduced in size until it is fine enough toiioat intheoutgoing steam. The separation of the fine particles takes place in twostagesfthe'first occurring as the material is initially fed into thetank. Any fines accumulated with the larger particles are immediatelyfloated upwardly .along with those resulting from repeated impact'sofpreviously fed particles. This preliminary dedusting of the enteringmaterial increases Vthe total output since it removes from 'the zone ofactive pulverizing that portion of the entering material. which isalready fine enough to Vrequire no further grinding. The second stageof'separation, of course, takes place in the classifier chamber 33, thefiner particles ascending from the center of the vortex with theoutgoing steam and the larger particles being thrown against the' Wallof chamber 33 and drawn downwardly into the hopper 44 and thence to theentering stream of 'fresh material.

Y The invention vhas the further advantage that the operating rate maybevaried without materially affecting the iinenesvs ofthe product. Thevolume of material'ground vmay be varied by changing the rate of feedand without altering the amount of steam. The steam consumption perpound of solid ground is such that the operating cost is not excessive.The apparatus is capable of grinding fuel 4with'as much as 10% moisture.This was impossible with previous de- 1 which are thrown to theoutskirts of the central vortex in the chamber andthe ffm'er, therefore,f

are the 'particlesijwhichactually,escape. The apparatus exhibits asatisfactorily low rate of wear despite the abrasivequality of thematerial being pulverized.

Operation lofthe apparatus `results in the building up of only a small yaccumulation of partlygground material inA the. bottom of vthe-tank andthis is. promptly disposed of 'when the input of A solidmaterial isdiscontinued.v The amountV of thisaccumulation, furthermore, does notbuild upas therate of operation is increased. v It will b e .understoodthat c :hanges inthe con,- stniction illustrated and described may bemade within the, .s,cope of my invention. Instead of l-lyng 01.1, theje? f nQQmDg; material-t0 Vpm" C1119? ,llf'tyQWldaftihpllgh theasseheeren a Seperate .Steam viet inieeier may 'be erhployed. Qn the otherhand, the hopper .may vbe constructed to deliver adjacent -the inletsofthe injectors 2d, les a further alternative provision af-heli'calflight'or vane may Ybe mounted inthe hopper ontheclassifier. Othermodiications metil alsbe made Asuch as utilizing thereduction-inpressure at the inlets oi 4the injectors to ydrawinfreshmaterial, instead of providing the'separate feeding y means shownat i3. The internal shape-offthe thro'at'slZ-l of the injectors may bevaried but that illustrated has proved toV be hignlxelective.

It will be understood that the aforementioned modiiications as well asother changes in the details of construction are contemplated within thescope of the following claims. Y

I claim:

l. In an impact pulverizer for solid particles, in combination, a closedchamber, a pair of horizontally extending injectors having open-endedthroats with both of their ends opening directly in said chamber, nozzlemeans for injecting a gaseous fluid under pressure through saidinjectors, said pair of injectors being coaxial and in opposed relationto one another across an unobstructed impact zone to force saidparticles to collide, means for withdrawing gaseous fluid and nnerparticles from said chamber at a vertically spaced zone above theinjectors, means for injecting a stream of solids and gas directly intosaid chamber between said withdrawal means and said injectors, .saidinjection being directed at a downward angle to a horizontal `planethrough the axes of said injectors and suiciently near the plane of theinjectors to assist in maintaining a circulation of the solids in saidchamber.

2. In an impact pulverizer for solid particles, in combination, a closedchamber, a pair of horizontally extending injectors having open-endedthroats with both of their ends opening directly in said chamber, nozzlemeans for injecting a gaseous fluid under pressure through saidinjectors, said pair of injectors being coaxial and in opposed relationto one another across an unobstructed impact zone to force saidparticles to collide, means for withdrawing gaseous fluid and finerparticles from said chamber at a vertically spaced .zone abovethe'injectors, means for injecting a stream of solids and gas directlyinto said chamber between said withdrawal means and said injectors, saidinjection being directed at a downward angle to a horizontal planethrough the axes of said injectors and suiciently near the plane of theinjectors to assist in maintaining a circulation of the solids in saidchamber, the interception of said angle with said plane being outsidesaid impact zone.

3;-, .11j-an impact ,pulverzergfer Solid particles; ineembinetienieclosed: chamber e reir ef herizon-tally extending i,njectors-A havingopen-ended throats with Vboth-V ottheir ends opening` directlyinsaidjcharnber.. I'nozzle means for injecting a easeeue .'.flurrunderpressure through. seid injecters, .Said pair Qf; inieetors beiney.coaxial vand in o pposedrelation to one Vanother acrossI an un-Qbstruetedimpeet zonel teioree Sa'df particles te er)A de,aelaeeervesselmeuntedfin seid chambe, v-.senferelly eboveaid injectors.means for withdrawing gaseous-iluidand finer particles from sai dehamber through said classifier vvessel,v said classiiieryessel having alower portion forming e-,heperhevine a'diseheree opening emptyinglntofsaid'chamber? to; return the coarser portions of said nnerparticles to said injectors, and means for injecting afstream of solidsand gas directly intosaid chamber betweenfsaid classifier vessel andsaid ,injectorsvsaid injection being directed at a `downward,'angle to.a horizontal plane through the axesof said injectorsand suiciently nearthe plane of vtheinjectors to-assist in maintaining a Circulation 0i theysolide in Seid chamberfl; lim-animpactpulverizer fornsolid particles,

in combination,arclosedgchamber, a .pair of hori-v zontally extending,injectors vhavingopen-.ended throatfsgwth bothfieftheirrends openingdirectly in said chamber, nozzle means for injecting a gaseous fluidunder pressure through said injectors, said vpair of injectors beingcoaxial and in opposed relation to one another across an unobstructedimpact zone to force said particles to collide, a classifier vesselmounted in said chamber generally above said injectors, means forwithdrawing gaseous fluid and ner particles from said chamber throughsaid classifier vessel, said classiiier vessel having a lower portionforming a hopper having a discharger opening emptying into said chamberto return the coarser portions of said finer particles to saidinjectors, and means for injecting a stream of solids and gas directlyinto said chamber between said classifier vessel and said injectors,said injection being directed at a downward angle to a horizontal planethrough the axes of said injectors and sufciently near the plane of theinjectors to assist in maintaining a circulation of the solids in saidchamber, said hopper being connected to said lastmentioned means toassist in the return of said coarserportions to said injectors.

5. In an impact pulverizer for solid particles, in combination, a closedchamber, a pair of horizontally extending injectors having open-endedthroats with both of their ends opening directly in said chamber, nozzlemeans for injecting a gaseous fluid under pressure through said`injectors, said pair of injectors being coaxial and in opposed relationto one another across an unobstructed impact zone to force saidparticles to collide, means for withdrawing gaseous iiuid and finerparticles from said chamber at a vertically spaced zone above theinjectors, an injector-type feeding means having its outlet mouthdischarging directly into said chamber immediately adjacent said impactzone between said withdrawal means and said injectors to assist inmaintaining a circulation of the solids in said chamber, said feedingmeans being directed ata downward angle to a horizontal plane throughtheaxes oi' said injectors, the axis of said feeding means lying in avertical plane normal to the plane through the axes of said injectorsand substantially eccentric relative thereto.

6. In an impact pulverizer :for solid particles,

7k in combination, a closed' chamber. a pair of horizontallyextendinginjectors having open-ended throats withboth of their endsopening directly in saidv chamber, nozzle means for injecting a gaseousiiuid under pressure through said injectors, said pair of injectorsbeing coaxial andin opposed relation to one another across anunobstructed impact zone to force said particles to collide, aAclassier-vessel mounted in said chamber generally above said injectors,means for withdrawing gaseous iiuid and finer particles from saidchamber through said classifier vessel, said classifier vessel having alower portion torming a hopper having a discharge opening emptying intosaid chamber to return the coarser portions of said iiner particles tosaid injectors, means for feeding gas and fresh particles to saidchamber between said classifier vessel andsaid injectors, said meansbeing directed at a downward angle-to a horizontal plane through theaxes of said injectors and sufiiciently near the plane ofthe injectorsto assist in maintaining a circulationof the solids'in said chamber, andgas feeding means to assist in the return of said coarser portions tosaid injectors and prevent any reversal in the direction of ow'in thelower portion of said classiervvessel. Y

- WILLIAM A. THOMAS.

8. .REFERENCES crrDf The following.references are of record in the le'of this' patent:V

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